The present invention relates generally to a shoulder replacement procedure, and more particularly to a method and apparatus for performing a shoulder replacement procedure in the treatment of cuff tear arthropathy.
During the lifetime of a patient, it may be necessary to perform a joint replacement procedure on the patient as a result of, for example, disease or trauma. One such type of joint replacement procedure is a shoulder replacement procedure in which a diseased and/or damaged shoulder joint is replaced with a prosthetic shoulder joint.
The need for a shoulder replacement procedure may be created by the presence of any one of a number of conditions. One such condition is the deterioration of the patient""s rotator cuff. Specifically, an intact rotator cuff stabilizes the humeral head in the glenoid fossa of the scapula during abduction of the arm. While it is stabilized in such a manner, abduction of the arm causes the humeral head to translate only a short distance in the superior direction (e.g. a few millimeters) whereby a space is maintained between the humeral head and the acromion. However, for patients with rotator cuff arthropathy, significantly greater humeral excursion is observed. In particular, hyper-translation of the humeral head in the superior direction is observed in patients with massive rotator cuff deficiency thereby resulting in articulation between the superior surface of the humeral head and both the inferior surface of the acromion and the acromioclavicular joint during abduction of the patient""s arm. Such articulation between these components accelerates humeral articular destruction and erosion of the acromion and acromioclavicular joint. Moreover, such bone-to-bone contact is extremely painful for the patient thereby significantly limiting the patient""s range of motion. In short, patients with massive rotator cuff tear and associated glenohumeral arthritis, as is seen in cuff tear arthropathy, may experience severe shoulder pain, as well as, reduced function of the shoulder.
In order to treat patients suffering from cuff tear arthropathy, a number of prosthesis and techniques utilizing existing prosthesis have heretofore been designed. For example, surgeons have heretofore utilized a relatively large humeral head prosthesis in an attempt to completely xe2x80x9cfillxe2x80x9d the shoulder joint space. It was believed that such use of a large prosthesis would increase the efficiency of the deltoid muscle thereby improving motion of the shoulder. However, clinical experience has shown that such use of a large humeral head prosthesis xe2x80x9coverstuffsxe2x80x9d the shoulder joint thereby increasing soft tissue tension, reducing joint range of motion, and increasing shoulder pain. Moreover, such use of an oversized prosthetic head fails to resurface the area of the greater tubercle of the humerus thereby allowing for bone-to-bone contact between the greater tubercle and the acromion during abduction of the patient""s arm.
A number of humeral head bipolar prostheses have also been utilized in an attempt to address the problems associated with cuff tear arthropathy. It was believed that the relatively unconstrained motion of the bipolar head would improve shoulder motion. However, heretofore designed bipolar prosthetic heads include relatively large offsets thereby overstuffing the shoulder joint in a similar manner to as described above. Moreover, scar tissue may form around the bipolar head thereby xe2x80x9cfreezingxe2x80x9d the dual articulating motion of the prosthesis which has been known to create a large hemiarthroplasty that likewise overstuffs the shoulder joint. In addition, such bipolar prosthetic heads do not cover the articulating surface between the greater tubercle and the acromion thereby creating painful bone-to-bone contact therebetween.
Yet further, a number of techniques have heretofore been designed in which the relatively rough surface of the greater tubercle is smoothened with an osteotome or high-speed burr. Although this approach results in a smoother tubercle contact surface, relatively painful bone-to-bone articulating contact still occurs thereby reducing the patient""s range of motion.
What is needed therefore is a method and apparatus for performing a shoulder replacement procedure for use in the treatment of cuff tear arthropathy which overcomes one or more of the above-mentioned drawbacks. What is particularly needed is a method and apparatus for performing a shoulder replacement procedure which eliminates painful articulation between the greater tubercle of the humerus and the acromion.
In accordance with one embodiment of the present invention, there is provided a method of performing a shoulder replacement procedure on a patient. The method includes the step of resecting a greater tubercle of a humerus of the patient. The method also includes the step of implanting a stem component into a medullary canal of the humerus of the patient. The method yet further includes the step of securing a prosthetic head component to a proximal end portion of the stem component. The prosthetic head component has a glenoid-bearing portion and an acromion-bearing portion. The glenoid-bearing portion of the prosthetic head component is configured to bear against a glenoid surface of a scapula of the patient subsequent to the implanting step and the securing step. The acromion-bearing portion of the prosthetic head component is configured to bear against an acromion of the patient during abduction of the humerus subsequent to the implanting step and the securing step.
In accordance with another embodiment of the present invention, there is provided a modular prosthetic assembly for use during performance of a shoulder replacement procedure on a patient. The assembly includes a stem component configured to be implanted into a medullary canal of a humerus of the patient. The assembly also includes a prosthetic head component configured to be secured to a proximal end portion of the stem component. The prosthetic head component has a glenoid-bearing portion which is configured to bear against a glenoid surface of a scapula of the patient when the stem component is implanted into the medullary canal of the humerus of the patient and the prosthetic head component is secured to the stem component. The prosthetic head component also includes an acromion-bearing portion which is configured to bear against an acromion of the patient during abduction of the humerus when the stem component is implanted into the medullary canal of the humerus of the patient and the prosthetic head component is secured to the stem component. The glenoid-bearing portion and the acromion-bearing portion of the prosthetic head component define an outer bearing surface. The outer bearing surface extends in a medial/lateral direction across a radial distance D in which Dxe2x89xa7190xc2x0.
In accordance with yet another embodiment of the present invention, there is provided a method of performing a shoulder replacement procedure on a patient. The method includes the step of resecting a greater tubercle of a humerus of the patient. The method also includes the step of implanting a stem component into a medullary canal of the humerus of the patient. Yet further, the method includes the step of securing a prosthetic head component to a proximal end portion of the stem component. The prosthetic head component has a glenoid-bearing portion and an acromion-bearing portion. The method yet further includes the step of positioning the glenoid-bearing portion of the prosthetic head component in bearing contact with a glenoid surface of a scapula of the patient. Moreover, the method includes the step of abducting the humerus so as to move the acromion-bearing portion of the prosthetic head component into bearing contact with an acromion of the patient.
It is therefore an object of the present invention to provide a new and useful apparatus for performing a shoulder replacement procedure in the treatment of cuff tear arthropathy.
It is moreover an object of the present invention to provide an improved apparatus for performing a shoulder replacement procedure in the treatment of cuff tear arthropathy.
It is a further object of the present invention to provide a new and useful method of performing a shoulder replacement procedure in the treatment of cuff tear arthropathy.
It is also an object of the present invention to provide an improved method of performing a shoulder replacement procedure in the treatment of cuff tear arthropathy.
It is yet another object of the present invention to provide a method and apparatus for performing a shoulder replacement procedure in the treatment of cuff tear arthropathy which eliminates painful articulation between the greater tubercle of the humerus and the acromion.
The above and other objects, features, and advantages of the present invention will become apparent from the following description and the attached drawings.